1. Field of the Invention.
The present invention relates to an apparatus for conveying and turning articles, expecially for utilization with article inspection or testing devices along the production line of a plant for manufacturing articles such as glass containers or vessels, wherein the article line conveying device comprises an article track, or path, defined by a conveyor belt arranged laterally thereof and a through belt arranged laterally thereof, in order to remove the vessels to be inspected from the conveying device of the production line and to feed them at intervals from one another into a testing station, and wherein the turning device is disposed at the testing station and comprises a control roller disposed on the one side of the track adapted to be displaceable between an operating position and a rest position, and two pressing rollers arranged sequentially in the direction of travel on the other side of the track and adjacent thereto, the front or entry pressing roller, considered in the direction of travel, being mounted upon a lever and pivotable transversely to the track, the three rollers cooperating together for the purpose of interrupting the travel of the vessels in the testing station and for rotating each vessel at least once about its axis. This invention is especially useful for testing apparatuses, in which the external shape and external dimensions of containers or vessels are inspected and cracks are detected in the vicinity of the vessel mouth, in order to reject these vessels which lie outside the predetermined fabrication tolerances.
2. Description of the Prior Art.
Because the effectiveness of the testing apparatus is very much dependent upon the functioning of the article line conveying and turning device, many devices are already known in many differing forms of construction, including those adapted for special operating conditions.
In a first device, which is described in U.S. Pat. No. 3,101,848 (Uhlig), the vessels to be tested are removed from the conveying device of the production line, which is normally constituted as a plate conveyor, and are conducted upon a curved track having a fixed floor to the testing station and are then returned from there to the conveying apparatus. The track is bounded at its external side by a guide rail and at its internal side by a circulating conveyor belt. The distance between the guide rail and conveyor belt is virtually equal to the diameter of the vessel to be inspected, so that this vessel is frictionally gripped by the conveyor belt and rolled along the guide rail. The guide rail comprises a gap somewhere about the middle of the track. At this point two freely rotating pressure rollers are mounted, which can be displaced by means of a cam disc transversely to the direction of travele. The cam disc also travel. a feed arm, which is disposed on the entry side of the track, so that the pressure roller are always displaced into the track when a vessel is situated in the region of the pair of rollers. The two pressing rollers then constitute, together with the opposedly situated conveyor belt, a three-point holder for the vessel, which is thus arrested in its conveyed motion and is rotated by the conveyor belt in this position until the pressing rollers are once again withdrawn from the track.
Another device, described in Swiss Patent No. 448,889 (Munz), also possesses a curved track having a fixed floor, of which the external side is bounded by a guide rail and the internal side by a conveyor belt. In this device also, the guide rail has a gap in the vicinity of the testing machine, and two freely revolving pressing rollers are provided at that position. Both pressing rollers are mounted upon pivoting levers and project, in their rest position, into the track. The pressing roller at the entry side can, when a vessel enters, be swung out from the track against the force of a spring, while the pressing roller on the exit side stops the entering vessel. Opposite to the two pressing rollers there is a driven friction wheel, the perimeter of which projects beyond the conveyor belt into the track and the circumferential speed of which determines the speed of revolution of each vessel held by the three rollers. To release a vessel from the testing station, the pressing roller on the exit side can be swung out from the track by means of an electro-magnet. The electro-magnet is regulated by means of a time switching apparatus, which is switched on when the entry pressing roller swings out.
In a further device known from U.S. Pat. No. 3,428,174 (Kulig), a curved track with a fixed floor is again used, the outer side of which track is bounded by a guide rail and the inner side by a conveyor belt. This device comprises, in the vicinity of the testing machine, a driven friction wheel which projects over the conveyor belt. On the side of the track opposite to the friction wheel, two pivotal levers are mounted. A portion of the guide rail is secured to the one lever, while two pressing rollers are fixed to the other. In addition, an electrical contact switch is provided at the entry side of the pressing station. By contacting this switch, each entering vessel causes that portion of the guide rail which is secured to the one lever to be swung back and simultaneously the two pressing rollers situated in their rest position externally of the track to be swung into the track, in which position they constitute, together with the friction roller, a three-point guide for the vessel which is to be rotated on the spot during inspection.
Finally, a device is known from U.S. Pat. No. 3,848,742 (Krenmayr), which likewise comprises a curved track having a stationary floor, in which a guide rail is mounted on the inner side and a conveyor belt on the outer side. In the vicinity of the testing station a friction wheel which can be driven at varying speed projects beyond the guide rail into the track, and two pressing rollers mounted upon pivoting levers can be swung, independently of each other, into the track above the conveyor belt. For the purpose of regulating the differing rotational speeds of the friction wheel and of the pivoting motions of each pressing roller, several electrical switches are provided at the entry side to the testing station, these switches being actuated by the entering vessel.
The devices described above possess at least three features in common. In all of them, the track constitutes an "adjacent track" to the conveying apparatus of the production line. The disadvantage of this is that all vessels must be deflected from this conveying apparatus into the device itself and, after passing through it, must be returned to the conveying apparatus.
Further, in these devices, the vessels are rolled in the track by means of a laterally applied conveyor belt against an opposedly situated guide rail. The peripheral speed of the vessels is thus twice their speed of translation. This means that, for equal translation speed, vessels of smaller diameter are rotated faster those those of large diameter, and are rolled along the guide rail. It will immediately be obvious to anyone skilled in this technology that the rolling of the vessels and their feed to the testing station at predetermined, equal intervals can only be guaranteed to an upper limit of speed which is a function of the vessel's size. On the other hand, in general, smaller vessels are produced at a more rapid rate than large vessels, resulting in the requirement that smaller vessels should be conveyed at larger translatory speeds through the device. A further disadvantage of the devices described above is that they can only satisfy this requirement within limits.
Finally, in the known devices, at least that pressing roller which is at the exit side is mounted upon a pivoting lever, which is so aligned relative to the through path that the pressing roller is pivoted practically transversely to the track. This leads to the further disadvantage that in particular those vessels which are heavy, if they are not round or possess nonuniform wall thicknesses, can push the exit side pressing roller sideways and thus "open" the three-point guide in the testing station.